Adapting a Frequency-Domain Optical Equalizer without Regressor Access

We consider the development of adaptive algorithms for use with an optical equalizer. The task of adaptively equalizing an optical signal has two notable challenges not present in traditional electrical equalization: 1) Access to a finite window of past equalizer inputs (i.e. the regressor) is impractical, and 2) The difficulty in building a true optical tapped delay line leads to implementations which are expected to have peculiar parameterizations as well as constraints on how the "taps" can be adjusted. We present a regressor-free algorithm suitable for adapting a prototype frequency-domain optical equalizer. In addition, we present trained and blind versions of the algorithm, and conclude with simulations demonstrating algorithm performance.